...and the debate continues. There is an interesting comment found in the March/April 2009 issue of American Handgunner.

On page 65 there is a picture associated with the article "S&W's Performance Center." The article was written by Roy Huntington.

The caption for the pic reads "Forged Performance Center (PC) parts on the left, MIM factory parts on the right. Is there a difference? The PC thinks so and spares no expense."

I have taken that to mean that while not necessarily bad, MIM parts are certainly not the best, at least not according to the very factory selling them.

While I have yet to read the article I don't see how I could take that comment out of context. It could be viewed as a slap in the face to many who have bought MIM equipped pistols after Smith said there was nothing wrong with them, only to refuse to use them in their premier line.

Of course it's up to you to buy what makes you feel good.

...and the debate continues. There is an interesting comment found in the March/April 2009 issue of American Handgunner.

On page 65 there is a picture associated with the article "S&W's Performance Center." The article was written by Roy Huntington.

The caption for the pic reads "Forged Performance Center (PC) parts on the left, MIM factory parts on the right. Is there a difference? The PC thinks so and spares no expense."

I have taken that to mean that while not necessarily bad, MIM parts are certainly not the best, at least not according to the very factory selling them.

While I have yet to read the article I don't see how I could take that comment out of context. It could be viewed as a slap in the face to many who have bought MIM equipped pistols after Smith said there was nothing wrong with them, only to refuse to use them in their premier line.

Of course it's up to you to buy what makes you feel good.

MIM parts are ugly looking, but completely servicable when properly made.

IMHO, the PC has no business copping an attitude these days about their "lofty standards" considering some of their guns I have had the misfortune to examine.... some of their guns look like they were fitted by Stevie Wonder. If they are so obsessed with quality, they ought to be able to make a new gun that locks up properly.

The MIM are ugly in a way, but the are great for making a comp gun out of. They are square and easy to polish and fit to each other. I like the guns off the regular line to use than some of the PC guns.

No question that the surface finish of forged parts can be made superior to MIM.

That doesn't make them superior in function.

PC, by virtue (supposedly) of the greater labor content of their processes, can accommadate the big limitation of forged parts in production: their greater dimensional variance. That's the theory anyway.

-- gearbox

I just used the search function and there were 79 pages where 'MIM' was posted.

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Bob

I don't believe the PC is what it used to be. I've owned two recent PC guns. One was OK, the other could use an action job, sideplate fit is not up to S&W standards (as I understand them), and has had lockup problems that have taken a while to get fixed. I object to paying for an action job on a PC revolver, so I'm switching out the forged hammer and trigger for my backup MIMs, which I expect to be much smoother.

From MachineDesign.com

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Bob

Exactly my complaint: I wanted a 627 8-shot because of the cool factor, and every one I looked at (brand new) needed work. Why should I pay over $1100 for a gun I have to overhaul?

I wish they offered the 627 8-shot as a standard production gun (for $400 less) so I wouldn't feel so bad about buying a new gun that needs an action job and a new hand right out of the box.

I could be wrong, but I believe the forged parts in a gun are certainly not hammered when they are piece parts. The bar material they are machined from is "forged" or probably hot rolled while still in semi raw state. Nobody bangs on things with a hammer any more that I know of.

The production drawback of "forged" parts is that machining parts from stock takes time and labor, and typically can not hold the tolerance an MIM part will so the forged piece requires final fitting.

equals easier to manufacture and cheaper to use MIM parts.

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ken
SWCA #1959

Forging in the metallurgical sense is heating and hammering.

Stamping may be closer to what you're thinking of.

There is also laser cutting, Electronic Discharge Machining.

The point is, in addition to cost savings, sometimes MIM produces a better part.

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Bob

albeit more porous as compared to forged.

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ken
SWCA #1959

They do and I have one.

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NRA Lifetime Member

If they exist, they are not legal in California. We have exactly one 627 8-shot legal for sale and it is a PC gun that sells for over $1100. RIDICULOUS.....

Slightly. The typical density of MIM is about 95 - 98% of forged, cast parts are about 60% (they are REALLY full of air by comparison).

[quote]Originally posted by 5Wire:
Sometimes, if the quality of the process is well controlled. The ****** reputation MIM now has is due to the poor QA the gun makers have by subcontracting their piece parts to the lowest bidder.

They heat and compress the bar stock which is later used to cut parts from, they don't beat on a cut piece until it is the shape they want.



[quote]Originally posted by 5Wire:
No, I am thinking of parts machined from forged stock.

Tell ya what, bountyhunter, look it up. That's what I did.

"• verb 1 make or shape (a metal object) by heating and hammering the metal." Oxford English Dictionary Online

"transitive verb1 a: to form (as metal) by heating and hammering b: to form (metal) by a mechanical or hydraulic press with or without heat" Mirriam-Webster Online

So, if you're machining from forged stock, how did it get forged and to what proximity of its final shape? The Forging process can use hydraulic pressure (or stamping) with dies or hammering, either way. Is that OK with your definition?

I'll add that just because a part is MIMd doesn't mean it's inferior or that the manufacturer deliberately accepts inferior OEMd parts just because the price is a low bid. In fact, I would say that in the arena of firearms manufacturers low bid is somewhere below #3 down the list of what's important to any outsourcing they might require.

The ****** reputation you claim for MIM is from people who don't know what they're talking about, not from metallurgists, or, in this case, reputable firearms manufacturers who actually employ metallurgists, listen to them, and perform tests-to-failure on new parts/materials before incorporating them in the products that keep them in business.

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Bob

I guess you really don't get it: here's the simple version:

The MATERIAL IS FORGED, NOT THE PIECE PART.

OK?

You can even find it in the description of hammers and sears on custom sites where it says something like: "CNC machined from forged moly steel and hardened to RC 52" or "CNC from forged tool steel" etc.

The point is, the material may be forged, but you have to cut the piece part out of the forged bar stock.

PERIOD.

They don't cut a part and then heat it and beat it like blacksmiths did to swords 500 years ago.

Uh- HUH. That's why the gun makers making 1911's started putting out ****** quality MIM extractors and safety levers that sheared or cracked. That's why somebody (I think it was Colt) later exploited the problem and marketed what they called "real steel" extractors machined from..... say it with me now... forged bar stock and charged higher prices for it.

Like I said, there is nothing inherently wrong with MIM, but when the process is poorly controlled it is subject to these catastrophic defects:

1) Air voids in the mold causing weak spots in the part.

2) Inconsistent slurry desnity if powder particle grain size is not uniform.

When MIM is poorly controlled, the probability of failure increases greatly in long thin pieces subject to shear force like extractors and safety levers.

Some people have an irrational fear of MIM based on ignorance and some people just don't get it in general.

I haven't seen any plague of fialures in SW parts made using MIM so I don't think they are a problem. Some people do.

Well, thanks for answering my questions, bountyhunter. You're a prince.

"Cut from forged bar stock": that would be cut by (milling) EDM, Laser, Bridgeport, or even die cut under pressure, as I posted. Is that right? The feed stock was forged in the sense of the definitions posted, correct? Hammered/hydraulically formed. I get it. But the part itself is not forged as you seemed to imply in earlier posts. Thanks for clearing up.

And as for low bidder, I referred to "reputable" manufacturers. 1911s have some of those among the hundreds who have taken on that design. The good ones changed their ways if things didn't work out. Most outsource placements I'm familiar with are based on quality, delivery, and competitive price (not necessarily low bid).

A long way around to more or less the same page.

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Bob

That's funny. And yea, I got one of Stevie's guns too, in fact I think I'll go hammer me up a new hand for it now....how do they get all those little dents out of them?

That's easy, the hard part is finding a place to buy the tiny anvil and hammer.....

You're entirely welcome.

Assuming proper procedures are followed, whether forged or MIM, metal parts can be defective for a number of reasons and that is the more likely source of failure rather than wear - so say my metalurgical friends.

Hi, folks. Some folks prefer MIM, some forged, but I personally don't believe that "they're both the same" or that its just a matter of taste or preference. There are differences in the two.

After single action firing my "classic" M36, I noticed scratch marks on the backstrap. When I posted a question, a few members suggested that I check the seam on the underside of the MIM hammer. I did. Sure enough, the MIM seam was nicking the backstrap. I sent the gun back to the factory; they "repaired" free of charge. Unfortunately, when I next single action fired the M36, similar nicks reappeared. While this sometimes can happen with forged hammers, you can file the offending portion of the hammer and not lose any structural integrity of the hammer. From what I understand, I don't think it's a good idea to file the seams on an MIM hammer, as it might compromise its integrity.

Funny thing....but Ruger has been making cast firearms for a VERY long time and I don't see them experiencing any problems related to casting.

Some of the best frames made were cast, even some high-end 1911's had cast frames. But, for the record, cast and MIM are not at all similar except for the fact they both use a mold.

cast material has less density than either MIM or forged material, but it still can make a good piece depending on what the requirements are. I don't think it's a good choice for small thin parts like extractors or safeties, but Para Ordnance did use cast extractors for a while. They were not great, but most worked OK if you didn't mind retensioning them frequently.

Not at all. An MIM part does not have seams. The mold it was in may have had seams which could put surface lines on the MIM part, but the interior of the piece is homogenous mmetal that is fused during the sintering process. Any surface lines are cosmetic. Filing an MIM part is no different than filing a cast or forged part. However, many hammers and triggers are surface hardened and filing through that can cause accelerated wear.

That is completely true. Even forged bar stock can have defects. The key difference is that both a cast part and a MIM part are molded and then put into service basically without much stress applied to it. If there is an internal defect it usually is not detected until it fails in service.

If a part is cut and machined from bar stock or tool steel, there is more of a chance it will fail during the cutting and grinding and not get into service. Of course, some bad parts get out regardless.

The misinformation and misunderstanding of sintered metal technology is staggering.

Looks aside, I can feel the difference in double action trigger pulls between my older S&Ws and the MIM actions.
Hard to describe, but I noticed the different feel years ago when they first came out with the newer MIM actions. They may break at the same poundage, but there is a difference how the two surfaces mate and interact.

Maybe it's the rebound slide. The new MIM ones are softer than the old hardened ones and dig into the frame a little more. I have to be honest, after I get done slicking mine up, I can't tell the difference in trigger pulls with MIM if both are equally tweaked up.

However, the new guns with frame mounted firing pins require about 1/2 pound more on the DA trigger because the FMFP takes a bit more pop to get the same level of strike energy.

Bountyhuner: I'm not an expert on such things. But some folks here mentioned "sintered" metal. I've worked with sintered metal. If it's the same thing as "MIM," in my opinion, I don't think that it is comparable to forged metal. In my experience, sintered metal didn't react the same as forged metal under certain stresses (e.g., sintered metal products tended to crack rather than bend) and when the surface is abraded, sintered metal products lost their structural integrity. I understand what you are saying about the seam in the mold; but I'm not sure that the seam on the MIM hammer is just a cosmetic result of the mold's seam. Whenever I've filed sintered metal products, the integrity of the product was compromised. Granted, these were not gun parts, but from what I've seen, I personally favor forged rather than sintered.

Perhaps someone who knows metallurgy quite well can help, but I always polish (wet'n dry paper) all my bearing surfaces to a high shine & remove all tool marks. Nothing fancy, but smooth as heck. And I've always felt the carbon steel parts have a bit less drag interacting and are just a bit more slick.

Having bought Smiths in the '70's I've felt some pretty gritty factory actions, something I've never encountered on the few MIM guns I've used. So I've tended to think off the shelf MIM beats the machined, but that with a bit of handwork the older internals interact smoother. Perhaps the MIM composition or that it is cast as a liquid presents a slightly less smooth surface?

The MIM part is metal powder that is heated hot enough to fuse solid. That step of the process is comparable to sintering.

Kind of depends on the definition of "comparable": MIM is about 95% - 98% as dense as forged stock or tool steel. It can be annealed or surface hardened exactly the same after fabrication. If properly made, an MIM piece is so close to a milled part in strength and hardness it is indistinguishable in service life. It clearly has a different appearance, and it holds tolerances so well it requires no fitting or machining after fabrication (the big cost saver).

All the data shows that a finished MIM piece is solid steel and behaves as one. It's ductility, tensile strength, etc will depend on what heat treatment and hardening it gets AFTER fusing solid.

If it is made right, it is a solid homogenous piece. If there is an internal defect it's an air void or grain size irregularity or dirt particle or something else.

Don't misunderstand: nobody is claiming an MIM part is SUPERIOR to a part milled from forged stock, rather it is NEARLY as good with respect to strength and servicability.... if and only if it is properly made.

If you don't mind paying even more for guns, they can use only machined parts. I think guns already cost way too much.

I read tons of posts from comp shooters who beat the **** out of guns. The routinely dump all the internals out of a new 1911 and spend $300 for new trigger, hammer, sear, disconnector etc without blinking.

For the SW guns, there has been no stampede of MIM failures. In fact, basically NONE of any volume. There were MANY 1911 extractor failures on new guns when they went to MIM but that was pobably a quality problem. My point is, if SW's MIM parts were ****, the comp shooters would be screaming it. They had no bones blowing the whistle on the C+S firing pins that failed frequently and often.

IMHO, when it comes to the hysteria about SW parts that are MIM it's all smoke.

[quote]Originally posted by sailing1801:
MIM is never a liquid. The metal powder is mixed with glue to make a slurry paste which is forced into the mold under pressure. That piece is removed from the mold and heated up to burn out the glue and fuse the metal powder (the part also shrinks to it's final size during this step). It's never liquid so it can't be poured into the mold like a cast part is, it has to be injected in.

For general info:


http://www.gknsintermetals.com/techn...mimprocess.htm



http://www.globalspec.com/reference/...on-Molding-MIM


http://www.remingtonpmpd.com/

MIM is not as durable as a forging. It will have a very slightly higher failure rate than forgings but not enough to cause cocern to the factory considering how much money they save.
However, even a very slightly higher failure rate means a lot to me in a product used to defend my life.
Colt stopped using MIM extractors several years ago because it was a poor application for MIM parts. Concrete is very strong for a post in compression but I would not want a concrete diving board. Colts MIM extractors were like concrete diving boards-not a good idea.
MIM is absolutely great for manufacturers in saving them time/money in fitting as the MIM parts are usually the correct size out of the mold.
I think one of the reason Glock has such a great reliability record is that it uses no MIM parts and the plastic used is a good application use. I have seen Kimber breakages with MIM parts and some will say that forgings can break too but I think no one has kept an accurate record or comparison though I am sure the firearms service departments have a good idea of this. The cost to failure ratio is acceptable to them.
You will never see MIM parts in critical aircraft components yet you see it in firearms.

If you want absolute, 100% reliability I recommend carrying a 2x4. After checking it carefully for knots, of course. If you decide, instead, to carry a mechanical device you'll have to accept that it's not perfect, and is subject to failure.

For those who still don't understand the MIM kind of process, you can get the materials and make decorative parts on your own! Find a jewelry crafts catalog or source.

They market products that look all the world like art supplies like modeling clay. The difference is in the price and components. You can get silver and gold. You can roll the stuff in your fingers, you can shape it with a knife or spatula, or with toothpicks, anything. When you get it to the general shape you want it, leave it sit out in the air. The clay dries out. Then you bake it in an oven or use a torch on it (not as good as the oven.) As it bakes or cooks, the clay appearance is cooked or driven out and what you end up with is a silver or gold trinket, the same shape as what you had when you let it dry. The difference is that its silver or gold. You can grind on it, polish it, sand it, or do whatever with it.

It won't be as hard or as good as a forged piece of gold or silver jewelry, but it will be an interesting exercise. Yes, my wife saw the stuff and had to have some. It was her project, and it was fun for her. Expensive, kind of, but we used the silver.

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Dick Burg

There is an appropriate place for cost-cutting installations. Colt may not make MIM extractors any more, but they do make and install plastic mainspring housings and triggers for the 1911A1 pistols. No doubt forged parts are the best. They are also the most expensive to make and fit. Springfield Armory makes their M1A receivers out of investment cast metal. They are quite good and many of them get heavy useage. There is also a manufacturer that makes the M1A with a hammer-forged receiver (LRB Arms of Long Island NY). They cost considerably more.
http://www.lrbarms.com/m14receivers.html

For civilian use, cast is more than adequate. For weapons that get extreme useage (the military puts thousands of rounds through their weapons), forged is better. The way I look at it....you wouldn't need a 10 pound sledgehammer to drive a thumbtack into the wall. An all-forged weapon would increase it's price to where many folks would never be able to afford it.

My understanding is that MIM parts are not cheap at all and, in fact, may cost more than their forged counterparts. They can save money because they don't require hand fitting or, as is often the case with S&W, hand misfitting.

That's true. But they are not the only company doing a brainlock on their extractors: Para used CAST extractors for a long time and they were much worse than MIM.

MIM is a poor choice for any long thin piece because any internal defect will cause a failure. BTW: the main problem with most 1911 extractors is they are made from steel which is simply too hard to reduce wear on the claw (hook). The 1911 extractor was specified as SPRING steel which may be interpreted to mean something springy, since the extractor must deflect over as the round slides up and return after it leaves. It has to be springy to hold tension, and the hard steel many are made from is why they have to be re-tensioned frequently.


Yes they do, but they X-ray them to make sure there are no defects.

I carry a crowbar myself, but only the FORGED kind. I have heard the MIM ones are not reliable....

That's what I always find interesting: MIM is much better than cast, but many high end guns are made using cast frames. I have never seen a thread about the evils of cast parts.

I have a few question to help me understand this debate.

1. What is MIM and what does it stand for.

2. Forged?

I have been playing with USFA and Colt SAA's for the last 10 years and am now coming home to the Smith and I am totally lost on this debate

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Slim, U.S. Army, Ret.

Slim, no disrespect, but in order to answer your questions to the point that you will be able to make an informed decision, someone is going to spend a significant amount typing a technical explanation. Some of us, in fact, have already done so in this forum.

Also, please do a search on your own using your internet search engine of choice. Find some websites that explain the metallurgy of forged steel and of metal injection molded steel. Then you will be well equipped to understand the discussion.

Most people who want to discuss this issue have neither the technical background nor the motivation to learn; and so they repeat erroneous ****, rumor, and theories they've heard all over the internet.

I appreciate that you do not want to be one of them, so please take my advice to do some research of your own. There's plenty of legitimate literature on both methods of forming steel out there for the taking.

You alreqdy answered my question. Injection moulding. I don't care about the metallurgy and the difference thereof, just that we are talking injection rather than forged. Good enuf for me and as long as it works, then I'm happy.

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Slim, U.S. Army, Ret.